CD28 Bioassay Components
The thaw-and-use format of the CD28 Bioassay Core Kit (Cat.# JA6701, JA6705) offers convenience and minimizes variability. The assay consists of the genetically engineered cell lines:
CD28 (TCR/CD3) Effector Cells: Jurkat T cells endogenously expressing TCR, CD3 and CD28 receptors and engineered with a luciferase reporter driven by a CD28 pathway-dependent promoter.
Based on the antibody properties to be tested, the CD28 Bioassay can be conducted with either aAPC/CHO-K1 Cells (Cat.# JA9441, JA9445) or FcγRIIb aAPC/CHO-K1 Cells (Cat.# JA9331, JA9335) to determine if the agonist antibodies can activate CD28 in an FcγR-dependent manner. These cells must be purchased separately.
aAPC/CHO-K1 Cells (Cat.# JA9441, JA9445): CHO-K1 cells engineered to express a cell-surface protein designed to activate the TCR complex in an antigen-independent manner. Intended for use with FcγRIIb-independent antibodies or other biologics that do not require crosslinking for optimal activity.
FcγRIIb aAPC/CHO-K1 Cells (Cat.# JA9331, JA9335): CHO-K1 cells engineered to express a proprietary TCR-activating protein as well as human FcγRIIb. FcγRIIb serves as a crosslinking receptor that binds to antibody Fc domains and clusters agonist antibodies for maximal agonist activity.
The CD28 Effector Cells and FcγRIIb CHO-K1 Cells are also available in Cell Propagation Model format (CPM; Cat.# JA1072) as cryopreserved cells that can be thawed, propagated and banked for long-term use.